Fig. 2.
Microtiter replica plates used to identify transfer-up mutants. The example shown is the result of a single 96-well mating assay replica-plated onto trypticase soy agar plates. (A) Hyg-containing trypticase soy agar medium selecting for donors. (B) HygSm-containing trypticase soy agar medium selecting for transconjugants. The spot boxed at 8E is an example of an up-mutant. Note the confluent growth of 8E transconjugants compared with the speckled growth of other spots. Controls are indicated in rectangles and were as follows. Column 11 contains wild-type donor cells only, and consequently growth is only observed on plate A. In row H, wells 1–10 contain recipient cells only, which cannot grow on either plate A or B. In column 1, rows A–G contain wild-type donor and recipient and represent normal levels of Hygr transfer on plate B.